System for guiding media in an imaging apparatus

ABSTRACT

A guiding system for diverting media from an input media path to an output media path in an imaging system eliminates marking and curling of media. The system employs a drive roll, an idling belt carried on one or more idler rolls, and a release roll. The idling belt presses media onto the drive roll, eliminating the relative motion between media and the drive roll and hence avoiding marking. The penetration of the release roll into the drive roll controls curling of media.

TECHNICAL FIELD

The presently disclosed embodiments relate to image-forming devices,such as printers, copiers, and similar imaging apparatus, and moreparticularly, to devices that guide media within an imaging system.

BACKGROUND

An image-forming apparatus, such as a printer, a fax machine, or aphotocopier, includes devices for directing sheet media along a mediapath. Conventionally, imaging devices employ baffles, diverters,rollers, or similar devices to perform that task. A media path generallybegins with an input section for introducing media and includes atransfer area where media receives an image, and it may further includean output section where sheets exit from the image-forming apparatus.

Media rounding a bend in a media path are typically subjected to twotypes of damage—marking and curl. Marking refers to undesired spots orlines on media surface caused by the relative motion of media against aguiding device and the contact pressure between them. Curl, as the namesuggests, is a deformation resulting in a loss of flatness of a mediasheet.

Known sources of curl, for example, are devices employed to fix tonerimages formed on sheets in the image-forming apparatus. Most imagingdevices, such as copiers and printers, employ a pair of rollers toperform the fixing operation employing pressure and heat. To supplysufficient heat to the toner image, a prescribed nip is formed betweenthe rollers and satisfactory fixing proceeds by passing the sheetthrough this nip. After that operation, however, the sheet may exhibitcurl imparted by the rolls. Another known source of curl is a change inhumidity. Whatever the cause, curl renders media susceptible todeformation and causes jamming during sheet transfer.

One approach to avoiding marking and curl aims to ensure that allchanges of direction in the media path occur over relatively largediameters. One example, in equipment processing a variety of differentmedia, specifies that all changes of media path direction occur onturning radii of at least 150 mm. While measures in that direction canhelp control marking and curl, those solutions increase machine size andcost, detracting from these solutions' attractiveness.

Direct measures aimed at reducing marking and curl have also beenattempted. One approach subjects sheets to “reverse curl,” in anoperation that seeks to deliberately impart curl, but in an oppositedirection to the prevailing direction of curl damage. For example,sheets curling toward the printed side can be straightened by impartinga curl in the opposite direction, toward the blank side.

Present damage control techniques have been effective for only a narrowrange of media weights, however. Specific implementations of reversecurl techniques, for example, are not reliable across a spectrum ofmedia weights. Typically, these techniques are effective for only asmall range of media weights, and any curling of media outside thissmall range is not uniformly effective. Heavyweight, stiff, and coatedmedia are especially sensitive to both types of damage. Existingadjustable devices may impart curl on a large range of media weights,though they are typically quite expensive. For example, the IGEN4imaging system, commercially offered by Xerox Corporation, employs anadjustable decurler that varies the nip pressure to impart curl on mediawith densities ranging from 60 gsm to 350 gsm.

Improved image quality and increased speed of image-forming devices hasincreased the variety of media run on them. Thus, there remains a needto provide compact and inexpensive image-forming devices for sensitivetypes of media. Further, the image-forming devices require a mediadiverting system, preventing marking and curl.

SUMMARY

The present disclosure describes an apparatus for diverting media froman input media path to an output media path in an imaging system. Theapparatus employs a drive roll, an idling belt carried on one or moreidler rolls, and a release roll. The idler belt is in contact with thedrive roll between an input nip, which accepts media from the inputmedia path, and the output nip, where media is output to the outputmedia path. A release roll, also an element of the diverter beltassembly, penetrates into the drive roll. As a result of the cooperativeaction between the drive roll and the idling belt, the media and thesurface of the drive roll have identical velocities.

Certain embodiments include apparatus for diverting media from an inputmedia path to an output media path in an imaging system. The apparatusemploys a drive roll, the surface of which is formed of a resilientmaterial. Further, the apparatus includes an idling belt, carried on oneor more idler rolls and a release roll, in contact with the drive roll.The idling belt is configured to be driven solely by interaction withthe drive roll, so that no relative motion exists between contactingpoints on the drive roll and the idling belt. The release roll, formedof a material harder than the material of the drive roll, is adjustablypositioned to penetrate into the drive roll to a predetermined depth.The idling belt makes contact with the drive roll between an input nip,located for accepting media from the input media path, and an outputnip.

Another embodiment includes a method for diverting a media path from aninput media path to an output media path in an imaging system. Themethod involves receiving media from the input media path. A drive rollholds media by employing an idling belt carried on one or more idlerrolls and eliminates relative motion between media and media pathsurfaces formed by the contact of the idling belt and the drive roll.The method further involves conveying media a predetermined angulardistance around the drive roll to an output nip point defined by thedrive roll and a release roll. The release roll is configured topenetrate the drive roll by an adjustable amount, imparting a reversecurl to the media, which is then released.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures described below set out and illustrate a number of exemplaryembodiments of the disclosure. Throughout the drawings, like referencenumerals refer to identical or functionally similar elements. Thedrawings are illustrative in nature and not drawn to scale.

FIG. 1 illustrates an exemplary embodiment of a media guiding system fordiverting media.

FIG. 2 illustrates a flowchart of an exemplary method for divertingmedia in a media guiding system.

DETAILED DESCRIPTION

The following detailed description is made with reference to thefigures. Exemplary embodiments are described to illustrate the subjectmatter of the disclosure, not to limit its scope, which is defined bythe appended claims. Those of ordinary skill in the art will recognize anumber of equivalent variations in the description that follows.

Overview

The present disclosure describes an apparatus and method for divertingmedia from an input media path to an output media path in an imagingsystem. Arrangement of the apparatus eliminates marking and curl inmedia rounding a bend in media path. The apparatus employs a divertermechanism, including a soft drive roll and a diverter belt assembly. Thediverter belt assembly operates in coordination with the drive roll anda release roll to redirect media without subjecting it to marking andcurl.

This apparatus provides a low cost compact media path design with smallmedia path radius, eliminating issues such as marking and curl of media,where these issues are a major concern for heavy, stiff, or coatedmedia.

It should be noted that the description below does not set out specificdetails of manufacture or design of the various components. Thoseskilled in the art are familiar with such details, and unless departuresfrom those techniques are set out, techniques, designs, and materialsknown in the art should be employed, and those in the art are capable ofchoosing suitable manufacturing and design details.

In the following description the terms “sheet” or “media” refer tosheets of paper, plastic, cardboard, or other suitable physicalsubstrate for printing images, whether precut or initially web fed andthen cut. The terms “media” and “sheet” are interchangeable and usedthroughout the disclosure.

DESCRIPTION OF EMBODIMENTS

FIG. 1 illustrates an exemplary embodiment of a media guiding system 100for diverting media. The exemplary embodiment of the media guidingsystem 100 may be employed within a device such as a copier, a printer,a facsimile machine, or a finisher that requires media diversion withoutany media damages. Various other embodiments can be anticipated toaddress many different systems or applications in which media needsdiversion.

The media guiding system 100 includes an input media path 102, a driveroll 104, a diverter idling belt 106 wrapped around multiple idlerrolls, such as idler rolls 110 and 112, and a release roll 114. Thedrive roll 104 presses against the diverter idling belt 106, forming aguiding surface for media. Further, the media guiding system 100includes an output media path 116.

The combination of the drive roll 104 and the diverter idling belt 106receives media from the input media path 102 through an input nip 108.The input nip 108 is the point at which the diverter idling belt 106makes contact with the drive roll 104. The output nip 118 is the pointat which the drive roll 104 makes contact with the release roll 114. Therelative position of the idler rolls 110 and 112 is arranged tofacilitate contact between the diverter idling belt 106 and the driveroll 104. Thus, the diverter idling belt 106 makes contact with thedrive roll 104 for an angular distance around the drive roll 104,governed by the positions of the input nip 108 and the output nip 118.From the output nip 118, sheets of media exits to the output media path116.

The drive roll 104 has generally an elastomeric surface, with analuminum core. Those skilled in the art will understand that a varietyof materials can be used to manufacture the core of the drive roll 104,such as stainless steel, iron, or lead. In general, the surface materialof the drive roll 104 is soft and spongy, such as, for example, urethaneor rubber. In any event, the surface material is chosen for itscharacteristics, preventing marking and curl. The hardness of thesurface of the drive roll 104 typically is selected to meet a number oftarget properties for the drive roll 104, such as the coefficient offriction, conductivity, compression set, abrasion resistance,elasticity, and cost, consistent with the type of media being conveyed.For example, the surface of the drive roll 104 may be chosen in ahardness range from 5 Shore A to 80 Shore D. Further, the drive roll 104radius is relatively small, of about 15 mm, creating a compactarrangement. In one embodiment of the present system, the drive roll 104is manufactured using a steel cylindrical core with a 10 mm radius,coated in an even 5 mm elastomeric layer or ‘skin,’ yielding the driveroll 104 with an outer-radius of 15 mm and having a skin formed of amaterial such as rubber, resin, urethane, EPDM, or other polymers. Thespecific material chosen for the skin exhibits properties consistentwith the media types envisioned for the particular apparatus. For ageneral-use imaging device, an appropriate material would be a urethanepolymer such as Rogers Corporation's ENDUR®-C.

The diverter idling belt 106 is a lightly tensioned belt rotating aroundthe idler rolls 110 and 112 and the release roll 114. The diverteridling belt 106 is generally made of rubber, having sufficientcoefficient of friction to carry media. The diverter idling belt 106 mayhave a suitable scale of durometer The media guiding system 100, asdepicted includes only two idler rolls 110 and 112; those skilled in theart, however will understand that the number of rolls within thediverter belt assembly may vary based on the arrangement of the mediaguiding system 100 and the position of the release roll 114. The idlerrolls 110 and 112 impart smooth and stable functioning of the diverteridling belt 106. The number of rolls depends on the length of thediverter idling belt 106 and the position of the release roll 114, asdiscussed, where the diverter idling belt 106 is dependent on thearrangement of the media guiding system 100. The diverter idling belt106 presses incoming media onto the drive roll 104, from the input nip108 to the output nip 118, so that the media sheet lies in contact withthe drive roll for the angular distance between the input nip 108 andthe output nip 118.

The release roll 114, also referred to as penetration roll, penetratesinto the drive roll 104, imparting a reverse curl in media. The radiusof the release roll 114 is relatively smaller than the drive roll 104,and this roll is formed from harder material than that of the drive roll104, such as steel or hard-plastic-coated steel. For example, the IGEN4system, noted above, uses a steel penetration roll in its decurlingdevice. The indentation of the release roll 114 in the drive roll 104helps control media curl, and this indentation may be set manually orautomatically at different levels.

Additionally, the point on the drive roll 104 where the release roll 114makes contact can be varied as desired, allowing the media to be held incontact with the drive roll 104 for exactly the angular distancespecified by the designer. Because media exits the output nip 118 on themutual tangent of the drive roll 104 and release roll 114, adjusting theposition of the release roll 114 also has the effect of varying theoutput media path 116. Where desired, that feature could be used invarious embodiments to allow for variable output media path 116.

Drive roll 104 is driven by conventional power means, typically anelectric motor, transmitting rotational force through direct gearing ora belt drive. The diverter idling belt 106 is not driven directly,however, but rather it is powered by the drive roll 104. Interactionbetween the drive roll 104 and the diverter idling belt 106, in the formof friction between these components' respective surfaces, serves todrive the diverter idling belt 106. As is known in the art, the frictionforce present in this system depends on the respective materials, theforce imparted by the diverter idling belt 106 to the drive roll 104resulting from the layout of the idler rolls 110, 112, and the totalarea of contact between the components. Here, a design criterion callsfor zero relative movement (that is, no slippage) between contactingpoints on the drive roll 104 and diverter idling roll 106, in thesituation where media is interposed between those elements. That lack ofrelative movement ensures that the media will not be subjected tomarking during the transport process. With those design requirements,those of skill in the art will be able to design specific embodiments tomeet particular functional requirements.

The media guiding system 100 may include a control mechanism, not shownin FIG. 1, to set the indentation level of the release roll 114 into thedrive roll 104. The control mechanism can employ any of the conventionalmeans to those in the art to set the release roll 114 indentation level.In one embodiment, the control mechanism includes sliding bearings alongslots or guides to support the release roll 114, controlling distancebetween the release roll 114 and the drive roll 104. Alternatively, astepper motor may rotate a shaft with cams, engaging support bearings.The stepper motor may rotate such that the cams engage the supportbearings more, pressing the release roll 114 into the drive roll 104depending on the desired indentation level. Another embodiment providesa non-dynamic arrangement that sets the indentation level manually,employing support bearings located with setscrews.

Those skilled in the art will be able to select a conventional controlmechanism, such as a computer-controlled mechanism, an electromechanicalmechanism, or any other suitable mechanism known in the art, for themedia guiding system 100.

The indentation level of the release roll 114 depends on the degree ofcurl required in media exiting the media guiding system 100. Forexample, if the release roll 114 does not penetrate into the drive roll104, the media exhibits an up-curl upon leaving the device. Increasingthe amount of penetration reduces the amount of up-curl, until the pointis reached where media emerges with a completely compensated, flatprofile. Further penetration produces a down-curl.

Thus, a particular imaging device that typically handles the same sortof media may be set to a single indentation configuration (noindentation, deep indentation, or medium indentation), designed tocounteract problems on that media only. Imaging devices that encounterfrequent media type changes can be provided with means for effectingconfiguration changes either manually or based on preset conditions.Those of skill in the art will be capable of implementing suchadjustment devices as required.

FIG. 2 illustrates a flowchart describing an exemplary method 200 fordiverting media from an input media path to an output media path in amedia guiding system. FIG. 2 describes the method 200 implemented by themedia guiding system 100.

At step 202, the input nip 108 receives media from the input media path102. Media enters the media guiding system 100 from the input media path102 to the input nip 108, at 4 point where the diverter idling belt 106makes contact with the drive roll 104. Media received at the step 202 isclamped to the drive roll 104 by the diverter idling belt 106 at step204. The adjustable idler rolls 110 and 112 facilitate this clampingoperation.

Then, at step 206, the media is released after travelling the desiredangular distance around the drive roll 104. As noted above, alternativeembodiments allow the output nip 118 to be adjusted among various pointson the surface of drive roll 104. Any such adjustment should becompleted before commencing a given operation of the imaging device, ofcourse. As media travels around the drive roll 104, the fact that themedia is being wrapped around the drive roll 104 in inherently tends toinduce curl, but the relatively large diameter of the turning radiusminimizes that tendency. Additionally, curl tendency will varyconsiderably with the media being processed. As noted in the art, aturning radius that will definitely impart curl to heavyweight media maynot affect lightweight media at all. Marking is also minimized becausethe design of the drive roll 104 and the diverter idling belt 106eliminates relative motion between media and media path surfaces.Further, the diverter idling belt 106, distributes pressure over theentire contact surface, reducing pressure at any given point, whichtends to minimize marking.

Step 208 ejects the released media to the output media path 116. Themedia travels around the periphery of drive roll 104 to the output nip118, at which point it exits to the output media path 116.

As noted above, the amount of reverse curl imparted in the media dependson the indentation level of the release roll 114. For example, zeroindentation of the release roll 114 into the drive roll 104 may resultin a up-curled media, While increased indentation induces increased backcurl, until that point is reached at which media exits the drive roll104 with no curl whatsoever.

As can be appreciated, the disclosed method 200 does not require anyparticular sort of image forming apparatus. Both the system and themethod of this disclosure can be implemented in a wide range ofimage-forming apparatus.

It will be appreciated that several of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications. Thoseskilled in the art may subsequently make various presently unforeseen orunanticipated alternatives, modifications, variations, or improvementswithout departing from the scope of the invention, which is definedsolely by the claims appended hereto.

1. Apparatus for diverting media from an input media path to an outputmedia path in an imaging system, comprising: a drive roll; and an idlingbelt carried on one or more idler rolls and a release roll, such thatthe idler belt is in contact with the drive roll between: an input nip,located for accepting media from the input media path; and an outputnip, including the release roll, located for outputting media to theoutput media path.
 2. The system of claim 1, wherein the drive rollsurface is formed of a resilient material.
 3. The system of claim 1,wherein the idling belt is configured to be driven solely by interactionwith the drive roll, there being no relative motion between contactingpoints on the drive roll and the idling belt.
 4. The system of claim 1,wherein the release roll is formed of a material harder than thematerial of the drive roll.
 5. The system of claim 1, wherein therelease roll penetrates into the drive roll to a predetermined depth. 6.The system of claim 5, wherein the penetration of the release roll intothe drive roll is adjustable.
 7. The system of claim 6, wherein thepenetration of the release roll into the drive roll decurls the media.8. The system of claim 1, wherein the diameter of the release roll issmaller than the diameter of the drive roll.
 9. The system of claim 1,wherein the release roll is formed of steel.
 10. Apparatus for divertingmedia from an input media path to an output media path in an imagingsystem, comprising: a drive roll having a surface formed of a resilientmaterial; and an idling belt carried on one or more idler rolls and arelease roll, the idling belt being configured to be driven solely byinteraction with the drive roll, there being no relative motion betweencontacting points on the drive roll and the idling belt, and the idlingbelt being in contact with the drive roll between: an input nip, locatedfor accepting media from the input media path; and an output nip,including the release roll, located for outputting media to the outputmedia path; wherein the release roll is formed of a material harder thanthe material of the drive roll, and is adjustably positioned topenetrate into the drive roll to a predetermined depth.
 11. The systemof claim 10, wherein the penetration of the release roll into the driveroll decurls the media.
 12. The system of claim 10, wherein the diameterof the release roll is smaller than the diameter of the drive roll. 13.The system of claim 10, wherein the release roll is formed of steel. 14.A method for diverting media from an input media path to an output mediapath in an imaging system, the method comprising: receiving media fromthe input media path; holding the media against a drive roll employingan idling belt, wherein the idling belt is carried on one or more idlerrolls and there being no relative motion between contacting points onthe drive roll and the idling belt, conveying the media a predeterminedangular distance around the drive roll to an output nip defined by thedrive roll and a release roll, the release roll being positioned topenetrate into the drive roll to a predetermined depth; and releasingthe media to the output media path.
 15. The method of claim 14, whereinthe predetermined angular distance depends on the position of therelease roll.
 16. The method of claim 14, further comprising adjustingthe penetration of the release roll into the drive roll.
 17. The methodof claim 16, wherein the adjusted penetration of the release rolldecurls the media.